Mary and Donna lost on way to cabin?

Would love any help to identify the episode and season:

Mary and Donna are traveling at night, trying to find a cabin. They become lost, and are assisted by an officer/ranger, whose existence was later questioned. I think Mary and Donna may have been trying to prove they were capable of getting to the cabin on their own, without the help of the men.

I am sorry for the vague description, but these are recollections from watching it in the 60s. Would love to re-watch.